ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus GmbHGöttingen, Germany10.5194/acp-11-8017-2011European source and sink areas of CO<sub>2</sub> retrieved from Lagrangian transport model interpretation of combined O<sub>2</sub> and CO<sub>2</sub> measurements at the high alpine research station JungfraujochUgliettiC.12LeuenbergerM.12BrunnerD.31Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstr. 5, 3012 Bern, Switzerland2Oeschger Centre for Climate Change Research, Zähringerstr. 25, 3012 Bern, Switzerland3Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstr. 129, 8600 Dübendorf, Switzerland08082011111580178036This work is licensed under a Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/This article is available from http://www.atmos-chem-phys.net/11/8017/2011/acp-11-8017-2011.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/8017/2011/acp-11-8017-2011.pdf

The University of Bern monitors carbon dioxide (CO<sub>2</sub>) and oxygen (O<sub>2</sub>) at the High
Altitude Research Station Jungfraujoch since the year 2000 by means of flasks sampling and
since 2005 using a continuous in situ measurement system. This study investigates the transport
of CO<sub>2</sub> and O<sub>2</sub> towards Jungfraujoch using backward Lagrangian Particle Dispersion Model (LPDM)
simulations and utilizes CO<sub>2</sub> and O<sub>2</sub> signatures to classify air masses. By
investigating the simulated transport patterns associated with distinct CO<sub>2</sub> concentrations it is
possible to decipher different source and sink areas over Europe. The highest CO<sub>2</sub> concentrations, for example, were observed in winter during pollution episodes when air was
transported from Northeastern Europe towards the Alps, or during south Foehn events with
rapid uplift of polluted air from Northern Italy, as demonstrated in two case studies.
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To study the importance of air-sea exchange for variations in O<sub>2</sub> concentrations at
Jungfraujoch the correlation between CO<sub>2</sub> and APO (Atmospheric Potential Oxygen)
deviations from a seasonally varying background was analyzed. Anomalously high APO
concentrations were clearly associated with air masses originating from the Atlantic Ocean,
whereas low APO concentrations were found in air masses advected either from the east from
the Eurasian continent in summer, or from the Eastern Mediterranean in winter. Those air
masses with low APO in summer were also strongly depleted in CO<sub>2</sub> suggesting
a combination of CO<sub>2</sub> uptake by vegetation and O<sub>2</sub> uptake by dry summer
soils. Other subsets of points in the APO-CO<sub>2</sub> scatter plot investigated with
respect to air mass origin included CO<sub>2</sub> and APO background values and points with
regular APO but anomalous CO<sub>2</sub> concentrations. Background values were associated with
free tropospheric air masses with little contact with the boundary layer during the last few
days, while high or low CO<sub>2</sub> concentrations reflect the various levels of influence
of anthropogenic emissions and the biosphere. The pronounced cycles of CO<sub>2</sub>
and O<sub>2</sub> exchanges with the biosphere and the ocean cause clusters of points and lead to a seasonal
pattern.